This book did not begin as a theory. It began as a habit.
For many years I paid attention to something that most people consider trivial: plant structure. Not flavor, not calories, not vitamins, but structure — the firm, resilient architecture that plants build out of cellulose. Stems, fibers, ribs of leaves, the texture of roots. These parts of plants are usually ignored, softened, blended, or cooked into submission. Modern food culture is organized around making plants easier for humans to digest.
But what if digestion is not the whole story?
The human intestine is not an empty pipe waiting to be filled with nutrients. It is a living habitat, home to a dense community of microorganisms — the biome — that performs much of the chemical labor that keeps the human organism alive. These organisms need space, structure, and mechanical conditions in which to live and work. Their environment is the long chamber of the intestine.
Over time I came to see that cellulose plays a particular role in this environment. It is not food in the usual nutritional sense. Humans do not chemically digest it. Yet cellulose provides something else: physical presence, bulk, pressure, and continuity inside the intestinal tract. It occupies space and gives the biome something like terrain.
From this observation emerged a simple practice: the intentional use of cellulose in daily life.
To say “cellulose user” may sound unusual, but the phrase reflects a deliberate shift in perspective. Instead of viewing plants only as nutrient carriers for the human body, I began to view cellulose as infrastructure for the intestinal ecosystem. Eating plants became less about extracting molecules and more about maintaining the physical conditions in which the biome operates.
This book is not a medical manual and not a diet program. It is a set of reflections, experiences, and observations gathered over time. The ideas come from personal experimentation, from reading, from watching the body carefully, and from thinking about the relationship between humans and the microscopic world that inhabits us.
The chapters draw from a series of small essays written over the years — on the body and mind, on fasting, on the brain, on yoga, on pets, on the nature of being human, and on the possibility that caring for the biome may be one of the central responsibilities of human life.
Taken together they form a simple memoir: the story of someone who decided to take cellulose seriously.